Plate Boundaries and Volcanoes

Two different types of crusts. 

Continental Crust: Carries the land

Oceanic Crust: Carries water

This can be easily remembered, as the Ocean relates to water, and the Continental crust can be remembered for carrying the land, as the land is CONTinuous.

Plates are pieces of the earth's crust that have been broken up.

Convection currents are created when heat rises and falls inside the mantle.

• This is a product of radioactive decay in the core.

→ Plates are moved due to convection currents.

Plate boundary: The point where two plates meet

Constructive: Plates move apart Conservative: Plates slide past eachother

• Under sea
• Magma pushes up between two plates

Destructive: Plates move towards eachother

• Continental and Oceanic plate
• Oceanic forced underneath Continental - Oceanic denser
• Oceanic plate melts - forms magma - magma chamber
• Forms fold mountains - Alps and Himalayas

Supervolcano:

Eruptions are thousands of years apart. They are at a much larger scale. Magma is building up and eventually, gas and ash is released from thet op of the volcano, due to the bulge that has been formed.

Composite:

Made up of different amounts of lava and ash. Found at destructive plate boundaries. Mixture of hot steam, lava, ash, rock and dust. 

Shield:

Found at constructive plate boundaries. Eruptions are frequent but gentle. Caused by thin and runny lava.

Positive:

• Profit - scenery created from eruption attracts tourists
• Lava and ash deposited - nutrients for soil - agriculture
• Geothermal energy

Negative:

• Lives lost
• Lahars - mudflows created from ash and mud mixing with rain waiter/snow
• Settlements destroyed
• Landscapes destroyed/changed